pack-write.con commit Merge branch 'rs/blame-code-cleanup' into maint (a9508a1)
   1#include "cache.h"
   2#include "pack.h"
   3#include "csum-file.h"
   4
   5void reset_pack_idx_option(struct pack_idx_option *opts)
   6{
   7        memset(opts, 0, sizeof(*opts));
   8        opts->version = 2;
   9        opts->off32_limit = 0x7fffffff;
  10}
  11
  12static int sha1_compare(const void *_a, const void *_b)
  13{
  14        struct pack_idx_entry *a = *(struct pack_idx_entry **)_a;
  15        struct pack_idx_entry *b = *(struct pack_idx_entry **)_b;
  16        return hashcmp(a->sha1, b->sha1);
  17}
  18
  19static int cmp_uint32(const void *a_, const void *b_)
  20{
  21        uint32_t a = *((uint32_t *)a_);
  22        uint32_t b = *((uint32_t *)b_);
  23
  24        return (a < b) ? -1 : (a != b);
  25}
  26
  27static int need_large_offset(off_t offset, const struct pack_idx_option *opts)
  28{
  29        uint32_t ofsval;
  30
  31        if ((offset >> 31) || (opts->off32_limit < offset))
  32                return 1;
  33        if (!opts->anomaly_nr)
  34                return 0;
  35        ofsval = offset;
  36        return !!bsearch(&ofsval, opts->anomaly, opts->anomaly_nr,
  37                         sizeof(ofsval), cmp_uint32);
  38}
  39
  40/*
  41 * On entry *sha1 contains the pack content SHA1 hash, on exit it is
  42 * the SHA1 hash of sorted object names. The objects array passed in
  43 * will be sorted by SHA1 on exit.
  44 */
  45const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects,
  46                           int nr_objects, const struct pack_idx_option *opts,
  47                           const unsigned char *sha1)
  48{
  49        struct sha1file *f;
  50        struct pack_idx_entry **sorted_by_sha, **list, **last;
  51        off_t last_obj_offset = 0;
  52        uint32_t array[256];
  53        int i, fd;
  54        uint32_t index_version;
  55
  56        if (nr_objects) {
  57                sorted_by_sha = objects;
  58                list = sorted_by_sha;
  59                last = sorted_by_sha + nr_objects;
  60                for (i = 0; i < nr_objects; ++i) {
  61                        if (objects[i]->offset > last_obj_offset)
  62                                last_obj_offset = objects[i]->offset;
  63                }
  64                QSORT(sorted_by_sha, nr_objects, sha1_compare);
  65        }
  66        else
  67                sorted_by_sha = list = last = NULL;
  68
  69        if (opts->flags & WRITE_IDX_VERIFY) {
  70                assert(index_name);
  71                f = sha1fd_check(index_name);
  72        } else {
  73                if (!index_name) {
  74                        static char tmp_file[PATH_MAX];
  75                        fd = odb_mkstemp(tmp_file, sizeof(tmp_file), "pack/tmp_idx_XXXXXX");
  76                        index_name = xstrdup(tmp_file);
  77                } else {
  78                        unlink(index_name);
  79                        fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
  80                }
  81                if (fd < 0)
  82                        die_errno("unable to create '%s'", index_name);
  83                f = sha1fd(fd, index_name);
  84        }
  85
  86        /* if last object's offset is >= 2^31 we should use index V2 */
  87        index_version = need_large_offset(last_obj_offset, opts) ? 2 : opts->version;
  88
  89        /* index versions 2 and above need a header */
  90        if (index_version >= 2) {
  91                struct pack_idx_header hdr;
  92                hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
  93                hdr.idx_version = htonl(index_version);
  94                sha1write(f, &hdr, sizeof(hdr));
  95        }
  96
  97        /*
  98         * Write the first-level table (the list is sorted,
  99         * but we use a 256-entry lookup to be able to avoid
 100         * having to do eight extra binary search iterations).
 101         */
 102        for (i = 0; i < 256; i++) {
 103                struct pack_idx_entry **next = list;
 104                while (next < last) {
 105                        struct pack_idx_entry *obj = *next;
 106                        if (obj->sha1[0] != i)
 107                                break;
 108                        next++;
 109                }
 110                array[i] = htonl(next - sorted_by_sha);
 111                list = next;
 112        }
 113        sha1write(f, array, 256 * 4);
 114
 115        /*
 116         * Write the actual SHA1 entries..
 117         */
 118        list = sorted_by_sha;
 119        for (i = 0; i < nr_objects; i++) {
 120                struct pack_idx_entry *obj = *list++;
 121                if (index_version < 2) {
 122                        uint32_t offset = htonl(obj->offset);
 123                        sha1write(f, &offset, 4);
 124                }
 125                sha1write(f, obj->sha1, 20);
 126                if ((opts->flags & WRITE_IDX_STRICT) &&
 127                    (i && !hashcmp(list[-2]->sha1, obj->sha1)))
 128                        die("The same object %s appears twice in the pack",
 129                            sha1_to_hex(obj->sha1));
 130        }
 131
 132        if (index_version >= 2) {
 133                unsigned int nr_large_offset = 0;
 134
 135                /* write the crc32 table */
 136                list = sorted_by_sha;
 137                for (i = 0; i < nr_objects; i++) {
 138                        struct pack_idx_entry *obj = *list++;
 139                        uint32_t crc32_val = htonl(obj->crc32);
 140                        sha1write(f, &crc32_val, 4);
 141                }
 142
 143                /* write the 32-bit offset table */
 144                list = sorted_by_sha;
 145                for (i = 0; i < nr_objects; i++) {
 146                        struct pack_idx_entry *obj = *list++;
 147                        uint32_t offset;
 148
 149                        offset = (need_large_offset(obj->offset, opts)
 150                                  ? (0x80000000 | nr_large_offset++)
 151                                  : obj->offset);
 152                        offset = htonl(offset);
 153                        sha1write(f, &offset, 4);
 154                }
 155
 156                /* write the large offset table */
 157                list = sorted_by_sha;
 158                while (nr_large_offset) {
 159                        struct pack_idx_entry *obj = *list++;
 160                        uint64_t offset = obj->offset;
 161                        uint32_t split[2];
 162
 163                        if (!need_large_offset(offset, opts))
 164                                continue;
 165                        split[0] = htonl(offset >> 32);
 166                        split[1] = htonl(offset & 0xffffffff);
 167                        sha1write(f, split, 8);
 168                        nr_large_offset--;
 169                }
 170        }
 171
 172        sha1write(f, sha1, 20);
 173        sha1close(f, NULL, ((opts->flags & WRITE_IDX_VERIFY)
 174                            ? CSUM_CLOSE : CSUM_FSYNC));
 175        return index_name;
 176}
 177
 178off_t write_pack_header(struct sha1file *f, uint32_t nr_entries)
 179{
 180        struct pack_header hdr;
 181
 182        hdr.hdr_signature = htonl(PACK_SIGNATURE);
 183        hdr.hdr_version = htonl(PACK_VERSION);
 184        hdr.hdr_entries = htonl(nr_entries);
 185        sha1write(f, &hdr, sizeof(hdr));
 186        return sizeof(hdr);
 187}
 188
 189/*
 190 * Update pack header with object_count and compute new SHA1 for pack data
 191 * associated to pack_fd, and write that SHA1 at the end.  That new SHA1
 192 * is also returned in new_pack_sha1.
 193 *
 194 * If partial_pack_sha1 is non null, then the SHA1 of the existing pack
 195 * (without the header update) is computed and validated against the
 196 * one provided in partial_pack_sha1.  The validation is performed at
 197 * partial_pack_offset bytes in the pack file.  The SHA1 of the remaining
 198 * data (i.e. from partial_pack_offset to the end) is then computed and
 199 * returned in partial_pack_sha1.
 200 *
 201 * Note that new_pack_sha1 is updated last, so both new_pack_sha1 and
 202 * partial_pack_sha1 can refer to the same buffer if the caller is not
 203 * interested in the resulting SHA1 of pack data above partial_pack_offset.
 204 */
 205void fixup_pack_header_footer(int pack_fd,
 206                         unsigned char *new_pack_sha1,
 207                         const char *pack_name,
 208                         uint32_t object_count,
 209                         unsigned char *partial_pack_sha1,
 210                         off_t partial_pack_offset)
 211{
 212        int aligned_sz, buf_sz = 8 * 1024;
 213        git_SHA_CTX old_sha1_ctx, new_sha1_ctx;
 214        struct pack_header hdr;
 215        char *buf;
 216
 217        git_SHA1_Init(&old_sha1_ctx);
 218        git_SHA1_Init(&new_sha1_ctx);
 219
 220        if (lseek(pack_fd, 0, SEEK_SET) != 0)
 221                die_errno("Failed seeking to start of '%s'", pack_name);
 222        if (read_in_full(pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 223                die_errno("Unable to reread header of '%s'", pack_name);
 224        if (lseek(pack_fd, 0, SEEK_SET) != 0)
 225                die_errno("Failed seeking to start of '%s'", pack_name);
 226        git_SHA1_Update(&old_sha1_ctx, &hdr, sizeof(hdr));
 227        hdr.hdr_entries = htonl(object_count);
 228        git_SHA1_Update(&new_sha1_ctx, &hdr, sizeof(hdr));
 229        write_or_die(pack_fd, &hdr, sizeof(hdr));
 230        partial_pack_offset -= sizeof(hdr);
 231
 232        buf = xmalloc(buf_sz);
 233        aligned_sz = buf_sz - sizeof(hdr);
 234        for (;;) {
 235                ssize_t m, n;
 236                m = (partial_pack_sha1 && partial_pack_offset < aligned_sz) ?
 237                        partial_pack_offset : aligned_sz;
 238                n = xread(pack_fd, buf, m);
 239                if (!n)
 240                        break;
 241                if (n < 0)
 242                        die_errno("Failed to checksum '%s'", pack_name);
 243                git_SHA1_Update(&new_sha1_ctx, buf, n);
 244
 245                aligned_sz -= n;
 246                if (!aligned_sz)
 247                        aligned_sz = buf_sz;
 248
 249                if (!partial_pack_sha1)
 250                        continue;
 251
 252                git_SHA1_Update(&old_sha1_ctx, buf, n);
 253                partial_pack_offset -= n;
 254                if (partial_pack_offset == 0) {
 255                        unsigned char sha1[20];
 256                        git_SHA1_Final(sha1, &old_sha1_ctx);
 257                        if (hashcmp(sha1, partial_pack_sha1) != 0)
 258                                die("Unexpected checksum for %s "
 259                                    "(disk corruption?)", pack_name);
 260                        /*
 261                         * Now let's compute the SHA1 of the remainder of the
 262                         * pack, which also means making partial_pack_offset
 263                         * big enough not to matter anymore.
 264                         */
 265                        git_SHA1_Init(&old_sha1_ctx);
 266                        partial_pack_offset = ~partial_pack_offset;
 267                        partial_pack_offset -= MSB(partial_pack_offset, 1);
 268                }
 269        }
 270        free(buf);
 271
 272        if (partial_pack_sha1)
 273                git_SHA1_Final(partial_pack_sha1, &old_sha1_ctx);
 274        git_SHA1_Final(new_pack_sha1, &new_sha1_ctx);
 275        write_or_die(pack_fd, new_pack_sha1, 20);
 276        fsync_or_die(pack_fd, pack_name);
 277}
 278
 279char *index_pack_lockfile(int ip_out)
 280{
 281        char packname[46];
 282
 283        /*
 284         * The first thing we expect from index-pack's output
 285         * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
 286         * %40s is the newly created pack SHA1 name.  In the "keep"
 287         * case, we need it to remove the corresponding .keep file
 288         * later on.  If we don't get that then tough luck with it.
 289         */
 290        if (read_in_full(ip_out, packname, 46) == 46 && packname[45] == '\n') {
 291                const char *name;
 292                packname[45] = 0;
 293                if (skip_prefix(packname, "keep\t", &name))
 294                        return xstrfmt("%s/pack/pack-%s.keep",
 295                                       get_object_directory(), name);
 296        }
 297        return NULL;
 298}
 299
 300/*
 301 * The per-object header is a pretty dense thing, which is
 302 *  - first byte: low four bits are "size", then three bits of "type",
 303 *    and the high bit is "size continues".
 304 *  - each byte afterwards: low seven bits are size continuation,
 305 *    with the high bit being "size continues"
 306 */
 307int encode_in_pack_object_header(enum object_type type, uintmax_t size, unsigned char *hdr)
 308{
 309        int n = 1;
 310        unsigned char c;
 311
 312        if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
 313                die("bad type %d", type);
 314
 315        c = (type << 4) | (size & 15);
 316        size >>= 4;
 317        while (size) {
 318                *hdr++ = c | 0x80;
 319                c = size & 0x7f;
 320                size >>= 7;
 321                n++;
 322        }
 323        *hdr = c;
 324        return n;
 325}
 326
 327struct sha1file *create_tmp_packfile(char **pack_tmp_name)
 328{
 329        char tmpname[PATH_MAX];
 330        int fd;
 331
 332        fd = odb_mkstemp(tmpname, sizeof(tmpname), "pack/tmp_pack_XXXXXX");
 333        *pack_tmp_name = xstrdup(tmpname);
 334        return sha1fd(fd, *pack_tmp_name);
 335}
 336
 337void finish_tmp_packfile(struct strbuf *name_buffer,
 338                         const char *pack_tmp_name,
 339                         struct pack_idx_entry **written_list,
 340                         uint32_t nr_written,
 341                         struct pack_idx_option *pack_idx_opts,
 342                         unsigned char sha1[])
 343{
 344        const char *idx_tmp_name;
 345        int basename_len = name_buffer->len;
 346
 347        if (adjust_shared_perm(pack_tmp_name))
 348                die_errno("unable to make temporary pack file readable");
 349
 350        idx_tmp_name = write_idx_file(NULL, written_list, nr_written,
 351                                      pack_idx_opts, sha1);
 352        if (adjust_shared_perm(idx_tmp_name))
 353                die_errno("unable to make temporary index file readable");
 354
 355        strbuf_addf(name_buffer, "%s.pack", sha1_to_hex(sha1));
 356
 357        if (rename(pack_tmp_name, name_buffer->buf))
 358                die_errno("unable to rename temporary pack file");
 359
 360        strbuf_setlen(name_buffer, basename_len);
 361
 362        strbuf_addf(name_buffer, "%s.idx", sha1_to_hex(sha1));
 363        if (rename(idx_tmp_name, name_buffer->buf))
 364                die_errno("unable to rename temporary index file");
 365
 366        strbuf_setlen(name_buffer, basename_len);
 367
 368        free((void *)idx_tmp_name);
 369}